This invention is customized as to when the drilling operator is about to break into the seal or go into a formation which has unexpected pore pressures or fracture gradients. The seal is the impermeable rock barrier, under which the oil and/or gas is trapped. Once this seal is pierced, oil and/or gas can flow up through the well bore to the surface. Nevertheless, it is usually only estimated as to the exact depth, thickness and width of the seal as well as the vertical pressure thereunder. Thus, it can pose a danger to the drilling operator who is managing the pressures of the drilling operation who wishes to avoid a blowout. Also, petroleum engineers drill within a safety margin marked by an estimated pore pressure and by an estimated fracture gradient, with the weight of the mud (drilling fluid) and the frictional pressure of the drilling itself acting as to balance the pressure. If the mud weight and frictional pressure are too low, there could be a kick in that the pore pressure of the adjacent formation would exceed it. If the mud weight and frictional pressure are too high, it could exceed the fracture gradient and the formation can be damaged. Most drilling operations have blow out preventers at or near the surface. The flow of fluid up the drill string is already protected by back flow devices i.e. down hole float valves or IBOP (inside blow out preventers), which are in common use. This invention, the automatic down hole blow preventer is down hole and it can be activated by the early detection of the increased pressure of a kick. This early increased pressure will cause the activation of the external pressure deflector ring, which will flip up and out the external elastomer rings as to inhibit or block the further flow of fluid up the annulus. The automatic down hole blow out preventer works without mechanical valves, balls or other possible obstructions to the normal flow of mud in drilling operations and it is applicable to prevent an unexpected flow up the annulus. Depending on the elastomer used and the pressure of the kick, the automatic down hole blow out preventer can either block the kick or at least temporarily restrain the kick up the annulus until the surface blow out preventer is activated.
The automatic downhole blow out preventer system is composed of the following:    a. External elastomer rings as delineated in FIG. 3 (un-activated external elastomer ring). When activated, the external elastomer rings will flip up and out, thus blocking or inhibiting the passage of fluid in the annulus. The width of the first external elastomer ring will be at least the width of the annulus, plus an additional width as to be fitted under the permanent external metal ring.    b. Permanent external metal ring as delineated in FIG. 3, which acts to hold the upper portion of the first External Elastomer Ring from flying off when there is a kick.    c. Additional external elastomer rings as delineated in FIG. 3, with at least the width of the annulus, and with enough combined strength as to (when activated) block or inhibit the flow of the fluid up the annulus. An illustration of activated external elastomer rings are again delineated in FIG. 4.    d. External pressure deflector ring as delineated in FIGS. 3 and 4, which is designed to lift up the external elastomer rings.    e. Grooved section of the drill string to hold the external elastomer rings and the external pressure deflector ring as shown in FIG. 4.    f. An automatic release system so that the external pressure deflector ring will automatically be released from its position on the drill string (when the safety threshold pressure is reached) and the external pressure deflector ring will then move and push up and out the external elastomer rings as to block or inhibit the flow of fluid up the annulus    g. The automatic release system can be installed with the release mechanism being a breakaway metal shield ring as described in FIGS. 13 to 17. The metal shield ring is welded in place and the welds are designed to break or fail at the safety threshold pressure. This system has the advantage of protecting the external elastomer rings and external pressure deflector ring during drilling operations from abrasive mud and cuttings. It can also allow an extension of the cusps of the pressure deflector ring as described in FIGS. 18 and 19. It has the disadvantage of the welds could be damaged by normal drilling operations. Therefore, the rate of penetration and rotation speed of the drill string may need to be adjusted as to reduce the possibility of damage to the welds. A modification of this system is delineated in the alternative peg release sub-system, rim release sub-system or the weld release sub-system.    h. The peg release sub-system is illustrated in FIGS. 5 to 9 with metal pegs. It has the advantage of the pegs being adjustable as to their height. It has the disadvantage that the pegs may become loose during drilling operations. Therefore, the rate of penetration and rotation speed of the drill string may need to be adjusted as to reduce the possibility that the pegs may be jostled and their heights modified by drilling operations.    i. The rim release sub-system is illustrated in FIGS. 10 and 11. It has the advantage of having less parts and therefore, having a lower chance of failure. It also has the advantage that the height thereof will not be adjusted during drilling operations. It has the disadvantage of not being adjustable once the rim is installed or set in place on the drill string.    j. The weld release sub-system is illustrated in FIG. 12. It has the advantage of having fewer parts, and the weld is simply installed to break at a safety threshold pressure. It has the disadvantage of the weld could be damaged by normal drilling operations. Therefore, the rate of penetration and rotation speed of the drill string may need to be adjusted as to reduce the possibility that the weld may be damaged during drilling operations. The rate of penetration is exemplified as the penetration rate or drill rate and is the speed at which a drill bit breaks the rock under it to deepen the bore hole. The rotation speed of the drill string is exemplified as the speed of rotation of the drill string rotating around its axis and is the number of turns of the drill string divided by time, specified as revolutions per minute (rpm).